COMMENTS:I have not been there but found it on the web : picture gallery here:
story here Directions; take Seneca Road, South of Canyon Dam, off of HW 89 : Seneca is on the map at mapquest.com, search for Greenville, CA (plumas county) and it is there. REMAINS: wooden shacks, rusty digging artifacts

Historic Plaque reads: Seneca : Gold was found in 1851 and a wild mining town was born with a dance hall, feed store, livery, blacksmith, post office, grocery, rooming houses and a hotel with solar heated showers. The canyon's mine included the Sunnyside, Lucky Chance, White Lily, and Last Chance. A 10 stamp mill pounded out the ore. One mine had 500 Chinese miners; each earned 10 cents a day in rice and they had an opium den. The largest nugget found here was 42 ounces; worth $28,000 in 1942. The most famous spot was the gin mill run by Marie Sabin who moved here in 1934 with her husband Don. Marie was known as the guardian angel of Seneca.
Submitted by: Kathryn S. Davidson